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Question 1:

What level of oxygen saturation was used as a cutoff for initiation of supplemental oxygen for subjects in studies of asthma exacerbations?

Inpatient asthma team recommendation: Based on moderate quality evidence, the inpatient asthma team strongly recommends using supplemental oxygen to keep the patient’s oxygen saturation ≥ 90-92%. Pulse oximetry measurements are used to assess the severity of the exacerbation and the response to treatment. In infants and children, where the ability to perform FEV1 or PEF testing is diminished, monitoring SpO2 is essential. SpO2 less than 90-92% on room air is an indicator for hospitalization, therefore the goal is to keep SpO2 greater than or equal to 90-92% (EPR-3, 2007). The benefits of an oxygen saturation ≥ 90-92% outweigh undesirable effects. This recommendation applies to most patients in most circumstances. Further research (if performed) is likely to have an important effect on our confidence in the estimate of effect and may change the estimate. 

Literature (see Appendix A) supporting this recommendation:
The literature since (EPR-3, 2007) was searched and no new research was found. Boychuk, Yamamoto, DeMesa, & Kiyabu (2006) was referenced to support EPR-3 (2007) (See Table 1). Colorado Children’s Guideline (2011) states supplemental oxygen should be used for any child whose SpO2 is less than 90% and Cardinal Glennon’s Guideline (2009) does not give guidance on this recommendation. Ten citations were read to establish the oxygen saturation level utilized to determine therapy (see Table 2). 

Search strategy implemented:
PubMed performed February 26 2015:( There were no new citations that addressed the question since the 2010 search was performed).
("Asthma"[Mesh] AND ("Emergency Service, Hospital"[Mesh] OR "Emergency Nursing"[Mesh] OR "Emergency Medical Services"[Mesh] OR "Emergency Medicine"[Mesh] OR "Acute Disease"[Mesh] OR exacerbation[All Fields] OR attack[All Fields])) AND ("Oximetry"[Mesh] OR "permissive hypoxia"[All Fields]) AND ((Meta-Analysis[ptyp] OR Practice Guideline[ptyp] OR Randomized Controlled Trial[ptyp] OR Guideline[ptyp]) OR ("Cohort Studies"[Mesh] OR "Epidemiologic Studies"[Mesh] OR systematic[sb])) AND English[lang] AND ("infant"[MeSH Terms] OR "child"[MeSH Terms] OR "adolescent"[MeSH Terms])
19 citations 
CINAHL performed Sept 16, 2010:
S1 (MH "Acute Disease") Limiters - Exclude MEDLINE records Search modes - Boolean/Phrase
S2 (MH "Emergency Medical Services+") OR (MH "Emergency Service+") OR (MH "Emergency Nursing+") OR (MH "Emergency Medicine") Limiters - Exclude MEDLINE records Search modes - Boolean/Phrase. No citations
Table 1
Synthesis of relevant literature about oxygen saturation values to guide treatment of children with acute asthma exacerbations

Author, date, country, and industry of funding

Patient Group

Level of Evidence

Research design

Significant results


(Boychuk et al., 2006).

1219 encounters of 1008 unique children with acute asthma in 5 EDs/clinics, including urban, suburban, and rural settings.

Children were> 12 months and < 18 years, presenting with wheezing or bronchospasm. Convenience enrollment




Prospective cohort study.


Asthma severity was determined by NIH severity class groups.

Phase 1 subjects received usual care.

Phase 2 subjects received an educational video, and a written asthma action plan


Phase 1 and Phase 2 groups were similar except Phase 2 subjects were older. (Phase 1 mean age was 3.6 2.3 and Phase 2 mean age was 4.3 3.4 [p< 0.0001]).

The overall hospitalization rate was 15%.

The greater the severity classification, the higher the hospitalization rate.

The lowest severity group was least likely to have an asthma action plan.

Hospitalization rates by presenting oxygen saturation:

Presenting oxygen saturation

Admission rate

98% -100%












The mean O2 saturation across severity scores ranged from 96.0 +3.0 to 96.8+2.5. There was no significance among initial O2 saturation and severity score. Severity score was not related to admission rate.

Severity Score is a global score of asthma, not a measure of the event that brought the child to the ED. It is easy to confuse the term “severity score” in relation to the acute event versus the burden of the disease which the score measures.

The age difference between Phase 1 and Phase 2 subjects could be a concern for bias.

Some of the initial O2saturation measures may have been obtained with the subject receiving supplemental O2.



Table 2
Oxygen saturation level used to determine need for oxygen therapy in ten research papers and altitude of study location


Saturated oxygen values

Locations altitudes

(Kelly, Kerr, & Powell, 2004)

Mild > 94%, Moderate 94-90% and Severe < 90%

36 Australian centers various altitudes

(Keogh et al., 2001)

Used a saturated oxygen of < 92% to administer supplemental oxygen

Toronto Canada, altitude: 105 m. (347 ft.)

(Sole, Komatsu, Carvalho, & Naspitz, 1999)

92% was the cut off predicting the necessity to repeat treatment

Sao Paulo Brazil, altitude: 637 ft.

(Wright, Santucci, Jay, & Steele, 1997)

Pretreatment saturated oxygen < 91% was not useful in predicting admission/relapse (sensitivity 0.24, specificity 0.86, likelihood ratio of 1.77) and Post treatment saturated oxygen < 91% had a sensitivity of 0.34 and a specificity of 0.98 with a likelihood ratio of 16.43 to predict admission/relapse.

Providence RI, altitude: 50 ft.

(Keahey et al., 2002)

The mean saturated oxygen of children admitted was 93 + 5% and the mean saturated oxygen of children not admitted was 96% + 3%

44 Emergencies 18 in US states and 4 Canadian provinces. Various altitudes

(Carruthers & Harrison, 1995)

Adults 32% were smokers

Norwich UK, altitude: 30 m. (28 ft.)

(Mehta, Parkin, Stephens, Keogh, & Schuh, 2004)

In the group (n= 107) that needed < 4 hours of frequent bronchodilator treatment (FBT) presenting saturated oxygen was 95.5 + 2. In the group (n=166) that needed > 4 hours of FBT, presenting saturated oxygen was 93.3 + 3.8

Toronto Canada, altitude: 105 m. (347 ft.)

(Boychuk et al., 2006)

Presenting saturated oxygen < 90 related to increased hospitalization

Honolulu, HI, altitude: 4 m. (9 ft.)


First Author, Year

Saturated oxygen values

Locations altitudes

(Connett & Lenney, 1993)

Inpatients 75, all were children. All children required nebulization therapy with salbutamol 5 mg. Only those who required hospitalization were included in the study. Oxygen saturation was measured prior to nebulization and 10 minutes post nebulization. Children were awake. All received prednisone 2 mg/kg, PO. A post nebulization oxygen saturation that was < 91% best predicted the need for IV treatment (IV aminophylline and hydrocortisone).

Brighton, UK altitude: 0 ft.

(Geelhoed, Landau, & LeSouef, 1994)

Subjects: 280 children who were enrolled when the primary investigator was working. 198 were receiving episodic treatment and 82 were receiving regular treatment, including 11 who were on regular oral steroids. Treated in the ED with nebulized salbutamol. A minority (n = unknown) were given oral steroids. Subjects with a poor outcome (admission to the hospital) had a mean oxygen saturation of 92.4%, SD 3.2%. Subjects with a good outcome (discharged from the ED) had a mean oxygen saturation of 95 %, SD 2.0%.

Perth, Western Australia altitude: 66 ft.

These guidelines do not establish a standard of care to be followed in every case. It is recognized that each case is different and those individuals involved in providing health care are expected to use their judgment in determining what is in the best interests of the patient based on the circumstances existing at the time. It is impossible to anticipate all possible situations that may exist and to prepare guidelines for each. Accordingly these guidelines should guide care with the understanding that departures from them may be required at times.